Framed screened panels, such as are used for window screens, patio door screens and the like, are commonly made of four elongated frame members which are connected together at their opposite ends to form corners. The screen material, such as foraminous cloth-like screening, is conventionally secured to the frame members by holding its peripheral edges within open grooves that are formed along the inside edges of the frame members. An example of such a panel is disclosed in U.S. Pat. No. 3,321,885, issued May 30, 1967 to Pratt.
Commonly used frame members are formed in the shape of hollow, roughly rectangular shaped, tubes which are typically either extruded aluminum or roll formed sheet metal. These elongated frame members which make up the top, bottom and side parts of the frame, are ordinarily of uniform cross-section. Their opposite ends, normally, are mitered to form 45.degree. angle joints. The joints are rigidified and the ends of the frame members are interconnected by frame connector keys which generally comprise a pair of legs that are joined together at right angles. The legs are inserted within the adjacent open ends of the frame members and staked or otherwise locked to the frame members to form the joint. Examples of such corner constructions are disclosed in the foregoing patent to Pratt, U.S. Pat. No. 3,332,885 and in Bancroft, U.S. Pat. No. 2,717,667, issued Sept. 13, 1955, Kessler, U.S. Pat. No. 2,989,788, issued June 27, 1961 and Virkler et al, U.S. Pat. No. 3,606,419, issued Sept. 20, 1961.
Also, Weitzel, U.S. Pat. No. 1,852,866, issued Apr. 5, 1932 discloses a corner key connector, which is somewhat complicated in construction, to interconnect frame members having square cut ends, rather than mitered ends.
In the case of large screen panels, particularly those used for patio door screens and screens for larger windows, prior corner connectors have been inadequate to rigidify the panel enough to prevent twisting or bending of the panel. The twisting or bending of the panel out of its plane is particularly troublesome when the panel is removed from its support framing, such as for cleaning the window panel covered by it, and then attempts are made to replace it. However, the twisting or bending also presents problems during normal operation in that the screen may bind within its support tracks or outer support.
Thus, there has been a need for a rigid corner construction of a simple, inexpensive form which can be easily assembled or easily removed for replacement when desired. The invention herein is concerned with an improved corner connector key which forms an unusualy rigid corner construction for minimizing twisting or bending of the panel.